Photoassisted access to complex polyheterocycles containing a β-lactam moiety

•ESIPT-generated aza-o-xylylenes add to tethered furanacetic unsaturated pendants.•Complex polyheterocyclic β-lactams are formed despite the unfavorable energetics.•Postphotochemical transformations offer additional increase of molecular complexity.•Complex molecular architectures are accessible via few experimentally simple steps.

Intramolecular cycloadditions of aza-o-xylylenes generated via excited state intramolecular proton transfer (ESIPT) to furanacetic acid-based unsaturated pendants was shown to overcome the unfavorable energetics of the azetidinone ring formation, offering rapid access to β-lactams as primary photoproducts. These 2,3- and 3,4-dihydrofuran-containing reactive intermediates are suitable for a broad spectrum of postphotochemical transformations yielding complex polyheterocyclic molecular architectures possessing the β-lactam moiety.

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